The present disclosure relates to the field of remediation technology of trichloroethylene-polluted environments and involves a device and method of multi-method-combined remediation of trichloroethylene-polluted environments.
As an important volatile organic solvent, trichloroethylene (TCE) is widely applied to industries such as electroplating, dry cleaning and metal processing. Due to its extensive use and unreasonable discharge, it severely pollutes environments of soil and groundwater. TCE is a volatile organic compound with effects of carcinogenicity, teratogenesis and mutagenicity. Its degradation products are also toxic carcinogenic substances. In 1976, it was listed in 129 precedence-controlled pollutants issued by United States Environmental Protection Agency and the blacklist of China's environmental particular pollutants. Once TCE gets into an aeration zone or underground water, it usually exists long in various forms such as a phase of immiscible residual fluid, a dissolved phase, a gaseous phase and an adsorbed phase with low biological decomposability. As the half-life period of TCE in soil is about six to eighteen months, it exists long and pollutes environments severely after percolating through soil and underground water, which is extremely difficult to restore and control.
In consideration of universality of TCE pollution, harmfulness to human beings and complexity of its research and remediation, the remediation technology of TCE-polluting underground environments has become an issue attracting general attention at home and abroad in recent years. The present common methods can be divided into physical methods, chemical methods and biological methods. The physical methods mainly include gas explosion and active carbon adsorption. In the technology of gas explosion, a gas injection well is used to inject compressed air into an area with ground water pollution to remove pollutants by movement of air. As for active carbon, due to its large area, it can fully contact with pollutants to achieve adsorption and purification. The chemical methods are classified into methods of chemical chemical-reagent oxidation and photo-catalytic oxidation in which chemical reagents include H2O2, Fenton reagents, KMnO4 and O3 etc. Photo-catalytic oxidation refers to a method of removing contaminants in waste water by oxidation of catalysts under light of a certain wave length. Chemical reduction uses zero-valent iron and bimetallic particles to reduce TCE into less harmful hydrocarbon. The biological methods include technology of microbial remediation and phytoremediation. For microbial remediation, it primarily utilizes microorganism in natural environments or added microorganism to decompose pollutants. As to phytoremediation, it purifies contaminants in soil or water by functions of plants such as absorption, volatilization, rhizofiltration and stabilization.
Due to limitations of utilization of each method, a more effective device and method of soil remediation and purification is still needed.